Treatment of wool



FIFS SOE Patented June 10, 1952 UNITED STATES PATENT OFFICE TREATMENT OF WOOL ish company No Drawing. Application January 3, 1950, Serial No. 136,666. In Great Britain July 24, 1946 12 Claims. 1

This application is a continuation-in-part of our application Serial No. 751,472 filed May 29th, 1947, now abandoned.

This invention relates to a method of treatin materials composed wholly or partly of wool or of other animal fibres which are capable of being felted, in order to reduce the tendency of such materials to felt or shrink when washed in aqueous liquors and particularly when also subjected to mechanical movements. It further relates to a process of this kind, in which at the same time a bleaching eifect is obtained.

The method according to the invention is applicable to wool (which term is used in the specification to include not only sheeps Wool but also any other animal fibres which are capable of being felted in the form of loose fibres, slubbing, tops, roving, yarn, knitted or woven fabric or garments or in any other form). The wool material may be treated in the oily state, or may be scoured to remove the oil prior to the treatment.

It is known that wool may be rendered partially resistant to felting by treating with peroxides or peroxyhydrate bodies in alkaline solution, but this treatment leads to an undesirable degree of degradation of the wool if an attempt is made to obtain a high degree of shrink-proofing.

The object of the invention is to provide a treatment which can be controlled to give virtually any desired degree of shrink-proofing while causing minimum damage to the Wool and giving a product having a good handle.

A further object is to provide a treatment which gives a product having improved levelness of dyeing when dyed with the so-called colloidal or milling types of dye. A further object is to provide a treatment by means of which good or enhanced whiteness of the goods, i. e. a bleaching effect, may be obtained simultaneously with the shrink-proofing.

In the method according to the invention, materials composed wholly or partly of wool are impregnated with compounds of copper, nickel,

silver or mercury and are subsequently treated with solutions of peroxides or peroxyhydrate bodies. The presence of the metal compounds on the fibre produces a modification in the action of the peroxide, resulting in a greatly enhanced shrinkproofing effect as compared with the use of peroxides and so forth in alkaline solution in the absence of the metal compounds.

The degree of resistance to felting obtained depends on the following inter-related factors:

1'. The metal used and the concentration deposited on the fibre.

2. The temperature at which the metal compound is applied to the fibre.

3. Concentration of peroxide or peroxyhydrate.

4. pH of peroxide. etc., solution.

5. Temperature of peroxide, etc., solution.

6. Time of application of peroxide, etc., solu-- tion.

7. Liquor-to-goods ratio.

It is believed that the metals used owe their activating effect to the fact that they can exist in different states of valency, but we do not restrict ourselves to this explanation. The amounts of the metal compounds required are very small. the minimum amounts of metals expressed as a percentage of the weight of wool being 0.001% for copper or nickel, 0.03% for silver and 0.05% for mercury. As a rule it is preferred to use amounts between 0.002% and 0.15% and the maximum amounts which may be used without causing damage or discolouration of the wool are 0.15% in the case of copper and 0.75% in the cases of silver, mercury and nickel. It is preferred to apply the metal compounds at a temperature of not less than 50 C.

The materials may be placed in a solution of the metal compound and the temperature raised to the desired value and maintained at such value until the bath is substantially exhausted which may take about five or ten minutes.

When the metal used is copper, the levelness of the treatment may be further improved by pretreatment of the wool with a dilute solution of acetic acid.

When cellulosic fibres are present in the goods being treated, the preferred metal compound is a compound of nickel; some degree of decomposition of cellulosic materials is produced when peroxy-bodies react with such materials which contain copper.

Suitable peroxy-b'odies include peroxides of hydrogen, alkali metals and alkaline earth metals, perborates of alkali metals and percarbonates of alkali metals. The consumption is small and a standing bath may be kept to which additions may be made of peroxy-bodies to restore the original concentration and of other reagents to restore the original pH value.

The concentration of peroxy-bodies may be varied, but should not be so high as to cause degradation of the wool when applied for the desired time at the desired temperature. A higherv concentration may be used where it is desired to carry out the treatment in a shorter time or at a lower temperature. When hydrogen peroxide is used, it is in most cases possible to obtain good results by treatment for about 1 hour at 50-60 C. in a hydrogen peroxide solution of not more than six volumes and preferably about two volumes. Where a shorter time of treatment is desired, it would be possible to use a higher concentration of hydrogen peroxide, but it is believed that there would be no advantage in using a solution of more than about 20 volumes, especially in view of the greater cost of the more concentrated solutions. Corresponding concentration of other peroxy-bodies may be used. The minimum concentration which is practically useful would be equivalent to about 0.25 volume hydrogen peroxide, as any lower concentration would result in inconveniently long treatment times.

The pH of the solution of the peroxy-bodies may be varied over a wide range. The shrinkproofing effect is very small when the pH is less than about 3, but increases as the pH is increased above this value, although not in a linear manner. The pH value should not be appreciably greater than 10.5 especially if high temperatures are used. Where pH values lower than 10.5 are used, the treatment time required at a given temperature may be longer, although the relation is not linear, but the time required may be reduced by raising the temperature, as in general, with a given pH value, shorter times will be required when the temperature is higher.

The process according to the invention is not primarily a bleaching process, but in general it can be carried out without detrimentally affecting the whiteness of the goods, or with no more discolouration than can be removed by a subsequent clearing treatment. A certain amount of bleaching can, however, be obtained by selecting suitable operating conditions, and where enhanced whiteness of the goods, i. e. a bleaching effect, is desirable in addition to the shrinkproofing, the peroxy-body treatment should be carried out under alkaline conditions, i. e. at a pH of not less than 7.0 and not appreciably greater than 10.5, using a compound of either copper or nickel in the preceding impregnation.

It is essential in the process according to the invention that the specified small quantities of metal compounds should be used, and that the impregnation with metal compounds should precede the peroxy-body treatment. Treatment of wool with large quantities of metal compounds prior to peroxide treatment, or in a bath. containing metal compounds together with peroxybodies, results in absence of shrinkproofing, and gross discolouration of the wool.

The process may be carried out by immersing the goods in a bath of metal compound and subsequently immersing them in a bath of peroxy-body which has been brought to the desired pH value or by treatment in a machine in which the goods are held in a vessel and liquors are passed through by means of a pump or other device. Garments, socks, etc. may be treated in a paddle or rotary machine. The process may also be carried out by the padding technique.

It is advantageous to give a final treatment in acidified sodium bisulphite solution to assist in removal of metal compound from the fibres and to enhance whiteness.

The following examples are given as illustrations of the manner of carrying out the method according to the invention. All quantities are in parts by weight, except where otherwise indicated.

Example 1 100 parts of an all wool knitted underwear fabric in the secured state are treated in 3,000 parts of water containing 0.01 part of copper sulphate crystals. The temperature of the liquor containing the fabric is raised to C. and maintained at this temperature for about 10 minutes. The fabric is lifted and the liquor cooled to 50 C. when 60 parts by volume of volume hydrogen peroxide and 56 parts of sodium silicate Sp. Gr. 1.4 are added, giving a 2 volume hydrogen peroxide solution at pH 10.5. The fabric is entered and treated for 60 minutes at 50 C. About of the peroxide is used up. To improve the whiteness, the fabric is placed for 15 minutes in 3,000 parts of water containing:

7 .5 parts of sodium bisulphite. 3 parts sulphuric acid at 30 C.

On severe hand washing the original material shows an area shrinkage of 25.4% while the treated fabric has an area shrinkage of only 8.4%. The fabric has a superior white colour.

If desired, in order to further improve the levelness of the treatment, the wool may be pretreated for 10 to 15 minutes, before immersion in the copper sulphate solution, in 3,000 parts of Water at 35 C., containing 3.3 parts of 30% acetic acid. The wool may be transferred from this solution to the copper sulphate solution, or an appropriate amount of copper sulphate may be added to the acetic acid solution at the end of the pretreatment.

Example 2 100 parts of scoured 14/3 botany yarn are treated in 1,000 parts of water containing 0.25 part of copper sulphate crystals. The temperature of the liquor is raised to 50 C. while circulating through the yarn which is treated in a pressure dyeing machine. This temperature is maintained for about 10 minutes when 20 parts by volume of 100 volume hydrogen peroxide and 18 parts of sodium silicate Sp. Gr. 1.4 are added, giving a 2 volume hydrogen peroxide solution at pH 10.5. The liquor is circulated for 1 hour at 40 C. Approximately half the hydrogen peroxide is used up in the treatment.

A bisulphite treatment in a bath consisting of 1,000 parts of water, 2.5 parts of sodium bisulphite and 3 parts sulphuric acid is given at 30 C. for 15 minutes. The resistance to shrinkage of this yarn after knitting, when tested by severe hand washing and compared with the resistance to shrinkage of pieces knitted from the original yarn and from yarn treated in peroxide but without a previous metal treatment, gives the following results:

100 parts of an all wool knitted underwear fabric in the scoured state are treated in 3,000 parts of water containing 0.02 part of nickel sulpham. The temperature of the liquor containing the fabric is raised to 75 C. and maintained at this temperature for about 5 minutes. The fabric is transferred into 3,000 parts of water containing '75 parts of sodium perborate, this solution being at pH 10.1 at a temperature of 50 C. The temperature of the liquor containing the fabric is maintained at 50 C. for 1 hour. About half the available oxygen is used up and the pH is reduced to 9.9. A bisulphite treatment is given as in Example 1. The reduction in area after severe hand Washing is 13.8% compared with 26.0% for the original fabric.

Example 4 100 parts of all wool knitted underwear fabric in the scoured state are treated in 3,000 parts of water containing 0.08 part of copper acetate. The metal salt is applied to the material as in Example 1 and the fabric is then transferred to a solution containing 60 parts by volume of 100 volume hydrogen peroxide and 15 parts of trisodium phosphate in 3,000 parts of water, giving a 2 volume H202 solution at a pH 10.3. The fabric is treated for 60 minutes at 50 C. when about half the peroxide is used up. A bisulphite treatment is given as in Example 1. The area shrinkage after severe hand washing is 7.2%, compared with 18.7% for a treatment with the alkaline peroxide and 26.4% for the original material.

Example 5 100 parts of an all wool knitted underwear fabric in the scoured state are treated in 3,000

parts of water containing 0.02 part of copper sulphate crystals. The metal salt is deposited on the fabric'as in Example 1. A further solution is prepared comprising 3,000 parts of water and 105 parts of sodium percarbonate, giving a pH value of 10.3. The fabric is transferred to this liquor and treated in it for 1 hour at 30 C. A bisulphite treatment is given as in Example 1. The shrinkage resistance is considerably improved, giving 13.3% area shrinkage on severe hand washing compared with 26.0% in the original material.

Example 6 100 parts of scoured 14/3 botany yarn are treated in 3,000 parts of water containing 0.02 part of copper sulphate crystals. The metal salt is applied to the material as in Example 1. The yarn is then transferred to a solution containing 45 parts by volume of 100 volume hydrogen peroxide and 43.5 parts sodium silicate Sp. Gr. 1.4 in 3,000 parts of water (i. e. 1.5 volume H202 at pH 10.5). The yarn is treated for 60 minutes at 50 C. after which time of the peroxide is used up and is then transferred to a bisulphite solution as in Example 1. The shrinkage resistance is considerably increased as shown by the area shrinkage of 22.8% obtained by severely washing fabric knitted from the treated yarn, compared with 40% on fabric knitted from the untreated material.

Example 7 100 parts of a scoured light-weight hosiery web knitted from 36/2 botany yarn are treated in 3,000 parts of water containing 0.05 part of copper sulphate. The metal salt is applied as in Example 1. The fabric is then soaked for 4 hours in 2,000 parts of water containing 40 parts by volume of 100 volume hydrogen peroxide and 10 parts of hydrated tetrasodium pyrophosphate, giving a solution of pH 9.2. The temperature of the bath at the start is 50 C. and this slowly falls during the treatment. After rinsing in cold water the fabric is neutralised in 3,000 parts of water at 35 C. containing 3.3 parts of 30% acetic acid.

The reduction in area after milling a piece of the fabric for 2 hours with alkaline soap in experimental stocks is 8.5% compared with 34.0% for fabric which is similarly treated but omitting the copper sulphate, and 39. 6% for the original scoured fabric.

Example 8 100 parts of a scouredlight-weight hosiery Web knitted from 36/2 botany yarn are treated in 3,000 parts of Water containing 0.05 part of copper sulphate crystals. The metal salt is applied as in Example 1. The fabric is then dried and subsequently treated for 15 minutes at C. with a solution of 50 parts by volume of volume hydrogen peroxide and 2 parts of sodium acetate in 2500 parts of water. The peroxide loss is 30% and the pH value of the solution changes from 6.3 to 5.4 during treatment.

The fabric has an improved soft handle which is retained on washing.

The resistance to felting when subjected to alkaline milling for 2 hours in experimental stocks is of a high order. The area shrinkage is 5.2% against 35.4% for the original fabric.

Example 9 100 parts of 14/3 botany yarn in oil (in the unscoured state) are treated in a solution of 0.05 part copper sulphate crystals and 2.5 parts of a wetting agent in 1000 parts of water which is circulated through the yarn in a pressure dyeing machine. The metal salt is applied under the conditions given in Example 1. 1000 parts of a 2 volume hydrogen peroxide solution adjusted to pH 10.5 with 13 parts of sodium silicate sp. gr. 1.4 is circulated through the yarn for 1 hour at 50 C. The yarn is rinsed and subsequently scoured and exhibits a superior whiteness and handle.

Fabric knitted from this yarn when subjected to severe hand washing shows an area shrinkage of 21.8% compared with 40% for fabric knitted from the original yarn.

Example 1 0 100 parts of a scoured hosiery web knitted from 36/2 botany yarn are treated in 3000 parts of Water containing 0.25 part of silver nitrate. The metal compound is applied as in Example 1.

The fabric is transferred to a solution containing 60 parts by volume of 100 volume hydrogen peroxide and 54 parts of sodium silicate sp. gr. 1.4 in 3000 parts of water. Treatment is continued for 1 hour at 50 C. after which the fabric is rinsed in cold water and neutralizedin 3000 parts of water containing 3 parts of acetic acid (30%).

A severe hand washing test is applied and shows the following shrinkage when compared with the original fabric and the same fabric in which the metal treatment is omitted.

Percentage area shrinkage Fabric Original Untreated Alkaline peroxide on1y Silver nitrate/peroxide Example 11 3,000 parts of water containing 0.5 part of mercuric acetate. The metal compound is applied as in Example 1. A further solution is prepared comprising 3000 parts of water 60 parts by volume of 100 volume hydrogen peroxide and 54 parts of sodium silicate sp. gr. 1.4. The wool material is transferred to this solution and treated for 1 hour at 50 C. after which it is rinsed and given a neutralizing treatment in 3000 parts of water containing 6 parts of sodium bisulphite and 3 parts of acetic acid (30%).

The fabric shows high resistance to milling for 2 hours in experimental stocks. The area shrinkage is 12.7% against 30.3% for the original fabric.

Example 12 100 parts of scoured 14/3 botany yarn are treated in 3000 parts of water containing 0.025 part of copper sulphate crystals. The metal salt is applied to the material as in Example 1. The yarn is then transferred to a solution containing 180 parts :by volume of 100 volume hydrogen peroxide and 54 parts sodium silicate Sp. Gr. 1.4 in 3000 parts of water (i. e. 6 volume H202 at pH 10.1). The yarn is treated for 60 minutes at 50 C. After rinsing in cold water the yarn is neutralised in 3000.parts of water at 35 C. containin 3.3 parts of 30% acetic acid. The shrinkage resistance is considerably increased as shown by the area shrinkage of 15% obtained by severely washing fabric knitted from the treated yarn, compared with 35% on fabric knitted from the untreated yarn. The treated yarn is a fully bleached white in colour.

The metal impregnating solutions used in the above examples contain metal compounds in concentrations ranging from about 0.0003 to 0.025% by weight or from 3 to 250 parts per million (P. P. M.)

What we claim is:

l. A method of treating materials composed at least in part of animal fibres which are capable of being felted, such as wool, in order to reduce the tendency of such materials to felt and shrink when washed in aqueous liquors, comprising impregnating the materials with 0.001% to 0.15% of the weight of the wool of a copper compound and subsequently treating them with a solution of a peroxy-body, the pH of which is adjusted to a value not less than 7.0 and not appreciably greater than 10.5.

2. A method of treatin materials composed at least in part of animal fibres which are capable of being felted, such as wool, in order to reduce the tendency of such materials to felt and shrink when washed in aqueous liquors, comprising impregnating the materials with from 0.001% to 0.75% of the weight of the wool of a nickel compound, and subsequently treating them with a solution of a peroxy-body, the pH of which is adjusted to a value not less than 7.0 and not appreciably greater than 10.5.

3. A method of treating materials composed at least in part of animal fibres which are capable of being felted, such as wool, in order to reduce the tendency of such materials to felt and shrink when washed in aqueous liquors, comprising treating the material at a temperature of at least 50 C. with a solution of a compound of a metal selected from the group consisting of copper, nickel, silver and mercury, of such strength that the amount of metal present, expressed as a percentage of the weight of the wool, is 0.001%- 0.15% in the case of copper, 0.001%-0.75% in the case of nickel, 0.03%-0.75% in the case of silver and 0.05 %-0.75% in the case of mercury, until the metal compound in the solution is substantially exhausted, and subsequently treating the material with a solution of a peroxy-body at a pH of not less than 3 and not appreciably greater than 10.5 at a temperature of 30-80 C.

4. A method as claimed in claim 3, in which the materials are treated with a solution of a peroxy-body selected from the group consisting of hydrogen peroxide, peroxides of alkali and alkaline earth metals, and per-borates and percarbonates of alkali metals.

5. A method as claimed in claim 4 in which the concentration of the peroxy-body solution is the equivalent of between 0.25 volume and 20 volumes hydrogen peroxide.

6. A method of treating materials composed at least in part of animal fibres which are capable of being felted, such as wool, in order to reduce the tendency of such materials to felt and shrink when washed in aqueous liquors, comprising immersing the material in a dilute solution of acetic acid, treating it at a temperature of at least 50 C. with a solution of a copper compound of such strength that the amount of metal present, expressed as a percentage of the weight of wool, is 0.001 %-0.15%, until the solution is substantially exhausted, and subsequently treating the material with a solution of a peroxy-body at a pH of not less than 3 and not appreciably greater than 10.5, at a temperature of 30-80 C.

7. A method of treating materials composed at least in part of animal fibres which are capable of being felted, such as wool, in order to reduce the tendency of such materials to felt and shrink when washed in aqueous liquors, comprising treating the material at a temperature of at least 50 C. with a solution of a mercury compound of such strength that the amount of mercury present is from 0.05% to 0.75% of the Weight of the material, until the solution is substantially exhausted, and subsequently treating the material with a solution of a peroxy-body at a pH of not less than 3 and not appreciably more than 10.5, at a temperature of 30-80 C.

8. A method of treating materials composed at least in part of animal fibres which are capable of being felted, such as wool, in order to reduce the tendency of such materials to felt and shrink when washed in aqueous liquors, comprising treating the material at a temperature of at least 50 C. with a solution of a silver compound of such strength that the amount of silver present is from 0.03% to 0.75% of the weight of the material until the solution is substantially exhausted, and subsequently treating the material with a solution of a peroxy-body at a pH of not less than 3 and not appreciably greater than 10.5 at a temperature of 30-80 C.

9. A method of treating materials composed at least in part of animal fibres which are capable of being felted, such as wool, in order to reduce the tendency of such materials to felt and shrink when washed in aqueous liquors, and at the same time to obtain complete bleaching of the material, comprising immersing the material in a solution of a copper compound having a concentration of the order of from about 0.0003 to 0.025% by weight and of such strength that the amount of copper present is from 0.001% to 0.15% of the weight of the material, raising the temperature to at least 50 C. and maintaining it until the copper in the solution is substantially exhausted,

tion of hydrogen peroxide adjusted to a pH value of approximately 10.1, rinsing and neutralising with dilute acid.

10. A method as claimed in claim 3, in which the material is treated in a clearing bath such as acid bisulphite after the treatment with a peroxybody.

11. In the treatment of wool in order to reduce its tendency to felt and shrink when washed in aqueous liquors, the process which comprises treating wool at a temperature of at least about 50 C. with a solution of a compound of a metal selected from the group consisting of copper, nickel, silver and mercury, having a concentration of the order of about 0.0003 to 0.025% by weight and in such quantity that the amount of metal present, expressed as a percentage of the weight of the wool treated is 0.001 to 0.15% in the case of copper, 0.001 to 0.75% in the case of nickel, 0.03 to 0.75% in the case of silver and 0.05 to 0.75% in the case of mercury, until the metal compound in the solution is substantially exhausted, and then treating the fabric with a solution of a peroxy-body at a pH within the range of from about 3 to 10.5 at a temperature of from about 30 to 80 C.

12. In the treatment of wool in order to reduce its tendency to felt and shrink when washed in aqueous liquors, the process which comprises treating wool at a temperature of about 75 C. for about 10 minutes with a solution of copper sulphate having a concentration of the order of about 0.0003 to 0.025% by weight in such quantity that the amount of copper present is 0.001 to 0.15% of the weight of the wool, and subsequently treating the wool for about one hour at a temperature of about 50 C. with a solution of hydrogen peroxide of a strength of 1.5 to 6 volumes at a pH of 10.1 to 10.5.

PERCY WALMSLEY CUNLIFFE.

JOHN LESLIE SHARP.

FRANK ASHWORTH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS OTHER REFERENCES Goldthwait, Stability of Hydrogen Peroxide, Textile Colorist, June 1941, page 343.

Austin, Principles of Fur Bleaching, Textile Colorist, Dec. 1943, pages 519 to 521, October 1943, pages 429 and 430, 472.

Weisskopf, Fur Dyeing, American Dyestuff Reporter, March 29, 1943, pages 163 to 164. 

3. A METHOD OF TREATING MATERIALS COMPOSED AT LEAST IN PART OF ANIMAL FIBERS WHICH ARE CAPABLE OF BEING FELTED, SUCH AS WOOL, IN ORDER TO REDUCE THE TENDENCY OF SUCH MATERIALS TO FELT AND SHRINK WHEN WASHED IN AQUEOUS LIQUORS, COMPRISING TREATING THE MATERIAL AT A TEMPERATURE OF AT LEAST 50* C. WITH A SOLUTION OF A COMPOUND OF A METAL SELECTED FROM THE GROUP CONSISTING OF COPPER, NICKEL, SILVER AND MERCURY, OF SUCH STRENGTH THAT THE AMOUNT OF METAL PRESENT, EXPRESSED AS A PERCENTAGE OF THE WEIGHT OF THE WOOL, IS 0.001%0.15% IN THE CASE OF COPPER, 0.001%-0.75% IN THE CASE OF NICKEL, 0.03%-0.75% IN THE CASE OF SILVER AND 0.05%-0.75% IN THE CASE OF MERCURY, UNTIL THE METAL COMPOUND IN THE SOLUTION IS SUBSTANTIALLY EXHAUSTED, AND SUBSEQUENTLY TREATING THE MATERIAL WITH A SOLUTION OF A PEROXY-BODY AT A PH OF NOT LESS THAN 3 AND NOT APPRECIABLY GREATER THAN 10.5 AT A TEMPERATURE OF 30-80* C. 